The present invention relates to a pressure detection apparatus that is capable of detecting a pressure such as a cylinder internal pressure in an internal combustion engine, and more particularly to a pressure detection apparatus which has a pressure-sensitive resistor and a temperature-sensitive resistor and is capable of detecting the pressure correctly even if a temperature change occurs to the pressure-sensitive resistor.
In recent years, as a pressure detection apparatus that is capable of detecting a pressure such as a cylinder internal pressure in an internal combustion engine, there have been proposed and developed various pressure detection apparatuses having a Si device for detecting the pressure through a stress that occurs to the Si device itself according to the pressure by piezoresistive effect. For example, such pressure detection apparatuses have been disclosed in Japanese Patent Documents 1˜3 (see the following Related Art Documents).
In Patent Document 1, a force transducer (pressure detection apparatus) has a plate-shaped Si device for detecting a pressure, which is an object of detection, a pressure transfer block (pressing member) which is bonded to one main surface of the Si device and transmits the pressure to this main surface, and a base (supporting member) which is bonded to the other main surface of the Si device and supports the Si device (see FIG. 1 and its description in Patent Document 1). On the one main surface of the Si device, straight-shaped four gages (pressure-sensitive resistors) whose resistances vary according to the pressure are formed. Two of these gages extend in <110> direction, and the other two gages extend in <100> direction, then a bridge is arranged by these four gages.
In Patent Document 2, a force transducer (pressure detection apparatus) has a plate-shaped Si device for detecting a pressure, which is an object of detection, a force transmission block (pressing member) which is joined with one main surface of the Si device and transmits the pressure to this main surface, and a support bed (supporting member) which is joined with the other main surface of the Si device and supports the Si device (see FIG. 1 and its description in Patent Document 2). In Patent Document 2, one pressure-sensitive resistor whose resistance varies according to the pressure is provided in the force transducer.
In Patent Document 3, a physical quantity detection device (pressure detection apparatus) has a diaphragm type Si device, and a center portion (diaphragm portion) of the Si device, which receives a pressure that is an object of detection, is formed thin (see FIG. 1 and its description in Patent Document 3). On a surface of the Si device, two sensing resistors (pressure-sensitive resistors) are formed. One of two resistors, i.e. a first sensing resistor, is placed so that its own resistance increases when the center portion of the Si device bends upon receiving the pressure. The other resistor, i.e. a second sensing resistor, is placed so that its own resistance decreases when the center portion of the Si device bends upon receiving the pressure. The physical quantity detection device has first and second constant-current sources which supply predetermined first and second constant currents to the sensing resistors respectively. Then, in the physical quantity detection device, the pressure is detected on the basis of a potential difference between an electric potential of a connection point that connects the first sensing resistor and the first constant-current source and an electric potential of a connection point that connects the second sensing resistor and the second constant-current source.
(Related Art Documents)
    Patent Document 1: Japanese Patent No. 3317084    Patent Document 2: Japanese Patent No. 3166015    Patent Document 3: Japanese Patent Provisional Publication No. 2002-116105 (hereinafter is referred to as “JP2002-116105”)